[Chromoting] Let the webapp detect new clipboard text items when it gets focus.

remoting/webapp/document_proto.js

+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// This file contains type definitions for the remoting.Document class,
+// which is a subclass of Document.
+// It is used only with JSCompiler to verify the type-correctness of our code.
+
+/** @suppress {duplicate} */
+var remoting = remoting || {};
+
+/** @constructor

[Jamie, 2012/03/14 00:43:47]

You can annotate sub-classes via @extends. However, I think it might be better
just to add execCommand directly to the prototype of document, since that's
where it actually is. You can do away with the casts if you do that.

+ */
+remoting.Document = function() {};
+
+/** @type {function(string): void} */
+remoting.Document.prototype.execCommand;